756449 - profiling of a canvas2d program that runs at 30fps in Chrome but 20fps in FF hints at a JS bug

Status: RESOLVED WORKSFORME

(Core :: JavaScript Engine, defect)

Description

[Pomax]

apologies for the title, I honestly have no idea what the best concise description is. I wrote a 2d game engine in Processing, running in canvas2d through Processing.js and while this runs pretty nicely in Chrome (the demonstrator is intentionally limited to 30fps), it runs between 15-20fps on firefox. 

Highly relevant link: http://processingjs.nihongoresources.com/test/spritesD

When I ran this in the profiling nightly with XCode to see what it was doing (never did that before) it seemed to list 50% spent doing JIT things, which seems really high.

I don't know if this is a bug in JS/canvas2d, or something that surfaces only when running transcompiled code that makes use of a decent number of anonymous functions (due to the Processing.js rewrite of Processing to native JS) or whether it's something else altogether, but I'd love to find out (or hear about it).

Comment 1

[Pomax]

FPS information can be gotten by clicking the "toggle Statistics", which will pop up an overlay that plots the FPS value over time, listing how many unique actors are being used in computations per frame on the lower left, and the current frame rate value in the lower right.

Comment 2

[Mayank Bansal]

Seems smooth now.